Michigan Glacial Float Copper is a term given to Michigan native vein copper which has been removed from its natural geological deposits by glacial activity. During this era of time, continental ice flows carried and redistributed the copper as far as 500 miles away. Pieces may range in weight from less than an ounce into tons. These pieces of copper are most recognizable by the green patina which has developed on its surface due to its exposure to water, air and soil.